Submerged spiders spin silken scuba tanks
Common in northern and central Europe, the diving bell spider is the only spider that spends its whole life underwater, made possible by an amazing adaptation – the ability to spin a silken scuba tank!
The small (8-15mm) brown arachnids spin silken bubbles or “air bells” which supply oxygen, protect eggs and spiderlings, and provide a place to consume prey. The spiders are covered with tiny hairs, which trap bubbles of air when they swim to the water surface. The air bubbles are then transferred to the spider’s gossamer aqualung. In fact, the spider’s Latin name Argyroneta means “silvery net”!
The silken diving bell is cunningly designed. Its walls allow oxygen to diffuse into the air bubble and carbon dioxide to diffuse out, meaning the spider doesn’t need to regularly replenish it at the water’s surface.
An excellent swimmer, the spider will wait for prey to pass before seizing it between venomous jaws and retreating to its silk shelter. Whilst it feeds largely on small aquatic insects, its venomous fangs are large enough to piece human skin – leading to a painful itch!
Unusually for a spider, males are considerably larger than females. When mating, the male will (rather presumptuously) build a silk diving bell which connects to that of his intended female. After up to 70 eggs have been laid, the diving bell provides a safe nursery, sheltered from predators until the spiderlings are large enough to disperse.
Where to see?
The diving bell spider is common to ponds and lakes across north and central Europe. If you do go out pond dipping, please be careful of its painful bite!
- Behavioural ecology lab at the University of Bern
- The water spider at ARKive
- Water spider information at Buzzle.com
Videos at ARKive:
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